The right operation for the wrong reason in multi-focal non-small cell lung cancer

In a sixty-seven year old female smoker, a right lower lobe mass, intimately related to the mediastinum, was detected on computed tomography (CT) scanning. Bronchoscopy confirmed non-small cell lung cancer (NSCLC) and a subsequent integrated 18F-FDG Positron Emission Tomography (PET)/CT scan demonstrated a rim of non-FDG avid tissue between the lung tumour and the mediastinum, and no nodal or distant metastases. The patient was pre-operatively staged as cT3N0M0 and proceeded to exploratory thoracotomy. On histological examination of the resected right lower lobe, multiple deposits of bronchioalveolar cell carcinoma (BAC) were found surrounding a central adenocarcinoma, in addition to a small deposit of adenocarcinoma in a right upper lobe wedge resection sample. Neither the BAC deposits nor the upper lobe disease had been detected on integrated FDG-PET/CT scanning. The final pathological staging of this case (pT4N0M1 (stage IV)) is inconsistent with the improved survival rate of patients with multi-focal intrapulmonary NSCLC confined to the lung over other forms of T4 or M1 disease, particularly when the BAC cell type is involved. This case highlights these major limitations of the current TNM classification and discusses the increased risk of false negative results from integrated FDG-PET/CT scanning in the BAC form of NSCLC.